Concrete structure



Nov. 15, 1938. J, A. STRQMBERG 2,137,009

CONCRETE STRUCTURE Filed NOV. 27, 1956 5 Sheets-Shea?I 1 ,ggz

1 l0" 99'000 72900 80250 95000 3'000 2260 @l0/ia /25000 90500 90500 110'000 /33'000 3/20 Zoff. pn/ @W Nov. 15, 1938.

J4 A. STROMBERG CONCRETE STRUCTURE Filed NOV. 27, 1936 Nov. 15, 1938. J. A. sTRoMBERG CONCRETE STRUCTURE Filed Nov. 27, 1936 3 Sheets-Sheet 3 35W MW Patented Nov. 15, 1938 UN1TED sTATEs PATENT OFFICE coNcnE'rn STRUCTURE' application November zu, ma, serial No. naait 9 claims. (ci. '1alun` This invention relates generally to improvements in concrete'structures and has particular reference to light-weight concrete floor structures embodying a novel and economical design par- 5 ticularly adaptable to use in residences, apartments and other buildings.

An object of my invention is to provide a ilre resistant and structurally adequate door construction with the least volume, weight and cost i of material, and at a minimum expense of labor; such hoor construction including the novel use, construction and adaptation of precast members affording efilcient methods of manufacture and erection thereof. To meet these basic requirel ments I provide a novel system or combination .of precast joists and floor slabs. The floor slabs being preferably precast.

Another important feature oi my invention resides in the novel design of the bonding, interlocking and reinforcing details whereby the slabs and joists act integrally or in the manner of a T-section.

Another object of my invention is to produce a more perfect and eilicient T-beam action between the floor slab and joist, that is, to produce a strong andrigid joint between the slab and joist sections aiording a continuous slab. v

In a floor system of the T-section design, the bonding and interlocking element or joint be,-

tween the slab and the joist is stressed considerably by shear which obviously varies in unit intensity for different `design loads and spans.'

The ultimate shear resistance of such bonding and interlocking element between the slab and -f joist should provide an adequate safety factor and should be capable of developing the yield point strength of the joist reinforcemenh The primary object of this invention is'thre fore directed to the solution of the prcpblerrllof*` 40 the bonding joint between the slabs andy-joists and to produce a very elcient designjet. vfloor construction wherein the joist. and slab zfunc-` tion together as a T-section; the design permitting slight variations from exact joistspacing y by the use of spaced slabs and still affording conf.v

tinuity and stability of the finished floor slab system. H

provision of reinforcing members in the'` slabs and joists which reinforcing membersA 'are adapted to extend into a poured or cast-in-place bonding element to thereby interlock such bonding element with the adjacent slabs and sup-` porting inist. I6 Still another object of my invention resides looped in providing spaced slabs with battered and corrugated sides which features together with a poured bonding element, poured therebetween, resist the tendency of the slabs to lift in the bending of the joist and also aord an increase 5 in the moment of inertia in the design.

Myinvention contemplates also a novel floor system wherein the precast slabs and precast joists and the poured interlocking bonding elements areinterconnected together by extended l0 reinforcing members.

More specifically stated, an important feature of my invention resides in the provision of a floor system having precast joists and precast slabs and a.V poured interlocking bonding element 15 wherein for example:-

' 4(a) The Joist has a stem or web of minimum cross-sectional thickness with a slightly widened lower flange and an upper flange slightly wider than the lower ange. The lower and upper 20 flanges being reinforced respectively with tension and compression reinforcing members extending longitudinally of the beam. For light construction such as floors for dwellings, the lower flange may 'carry` one or preferably two longitudinally 25 extending reinforcing (tension) bars and the upper ilange a pair of spaced longitudinally extendingreinforcing (compression) bars tied together with suitably spaced light cross bars. The vertical shear reinforcing Aconsists, of suitably 30 spaceclflightr weight stirrups extending vertically through: the beam web and having ends looped aroundthe; tension reinforcing. bars in the lower flange-arid .intermediate portions or ends extend- "ingabovethe top of the beam fadapted to be 35 ,around the reinforcing bar in the poured dink? element. g .l ib) `:The'precastslabs are formed with down- ."Watdlyiputwardly battered opposite sides4 and thebatteredlisides' are corrugated. The corruga- 40 v tionsiextendtransversely of the slab. Each slab A'ded with suitable spaced reinforcing bars which xtend outwardly ci or beyond the corruab-l faces. The ends of these bars are hooked.v vThe extended portions of these efin' overlapping arrangement over the Another feature of my invention residesl'inflihe l 5015*' dare-adapted to be embedded Within the also preferably 'provided withga longitudinally extending reinforcing b ar around which I loop the outwardly projecting portions of the vertical 65 stirrups of the beam, thus tieing together .the beam with the bonding element.

It is also a feature of my invention to provide precast concrete beams with a plurality of openings spaced longitudinally of the beam and extending through and within the middle one-thrid section of the beam length to thereby secure a more effective section by directing and localizing the compressive stresses in the compression section of the beam above such openings and thus developing more of a truss action rather than a beam action.

Another feature of my invention is found in the utilization of such beam openings for passages for pipe or conduits and the like.

Still another object of my invention resides in the provision of a novel fire-resistant connection for precast beam ends which is particularly adaptable for use in framing headers or cross beams into spaced floor beams around stair wells; such connections including rigid steel saddles secured to the webs of the precast beams and a mass of concrete extending over and around such saddles to substantially cover such steel saddles.

With the above and other objects in view, my invention consists in the novel combination, construction and arrangement of the parts and members shown in preferred embodiment in the attached drawings, described in the following specifications and particularly pointed out in the appended claims.

In the drawings:

Fig. 1 is a sectional plan view showing a portion of a floor built in accordance with and embodying my invention;

Fig. 2 is a cross-section taken on line 2-2 of Fig. 1;

Figs. 3, 4 and 5, illustrate typical joist sections for dwellings embodying my novel beam design adapted for maximum spans respectively 16 feet, 20 feet and 24 feet;

Fig. 6 shows a table giving the approximate cross-sectional areas and weights of the 8, 10 and 12 inch joist sections shown in Figs. 3, 4 and 5;

Fig. 'l is a table showing the resisting moments, steel reinforcing required, and shear values for the three illustrated typical beam sections;

Fig. 8 shows a typical cross-section of a floor, a ceiling supported on the lower ends of the ioists and manner ofnmning electric wire conduits through openings in the beam webs;

Fig. 9 is a side elevation of a typical joist showing spaced openings in the middle one-third section thereof;

Fig. 10 is a modified cross-section of a floor wherein the electric wire conduits are run in the plane of spaced floor sleepers between the top wood door and the concrete floor slabs;

Fig. 11 is an enlarged cross-section taken on line ii-ii of Fig. 9 showing manner of supporting the ceiling channels to which suitable wire mesh is secured for a plastered ceiling;

Fig. 12 is an enlarged cross-section in perspective taken on line I2-I2 of Fig. 8 showing an opening in the web of the beam, a corrugated side of one of the door slabs and one of its reinforcing cross-bars extended into the space which is to receive the poured bonding section, and also showing the longitudinal reinforcing bar for the bonding section engaged by a Dair of the spaced beam stirrups;

Fig. 13 shows a plan view of atypical concrete precast floor slab;

Fig. 14 is a longitudinal section of the precast floor slab taken on line i4-i4 of Fig. 13;

Fig. 15 is a cross-section taken on line i'l-il of Fig. 13;

Fig. 16 is a plan view-of the precast beams showing the improved connections between a cross beam or header and between a beam framed into the header;

Fig. 17 is a cross-section taken on line I1-i`l of Fig. 16;

Fig. 18 is a view in perspective showing the metallic saddle adapted to receive the end of a beam.

In the concrete floor construction illustrated in Figs. 1 and 2, the walls of a building are indicated by 2l and the improved precast beams or Joists by 28. 'Ihe precast floor slabs are indicated by numeral 21.

The beam sections shown in Figs. 3, 4 and 5 are illustrative of precast floor Joists made in accordance with my invention for use in structures such as dwellings and are intended to support precast iloor slabs such as shown for example in Figs. 13, 14 and 15.

In my system of floor construction, the beam 28 may be described'as the T-beam type or design consisting of an upper flange 26^, a stem or web 28B and preferably a lower flange or widened section 280.

The lower section 26 which is under tensile stress is preferably reinforced with two spaced bars 2| extending longitudinally of the beam and the upper section 26A which is under compression is also preferably reinforced with two spaced bars 29 extendinglongitudinally of the beam.

'I'he reinforcing bars 28 are tied by cross members of heavy wire 30 having ends wrapped or looped around the bars 29.

Each beam 26 is reinforced with suitably spaced stirrups 2i consisting of a single wire having an intermediate looped portion 3|^ extending about the top of the beam and the ends of which extend through the stem or web 26B into looped or wrapped engagement with the tension bars 28 in section 28C.

Obviously the size of the wire stirrup 3i and the spacing of same will vary with the size,

spacing of and load on the beam. In the typical joist sections illustrated, these stirrups may be, for example, No. 7 wire spaced approximately six inches apart in the outer one-third sections of the beam and twelve inch spacing may be used in the middle one-third section.

I prefer to form the precast joists 26 with spaced circular open sections 26D extending through the web 26B. These openings 25D to be within the middle one-third section of the beam length, of a diameter not to exceed one-third of the depth of the beam and spaced approximately two to three times their diameter center to center. The use of these openings not only effects a saving of concrete but they form passages for pipe or conduit 32 as illustrated in Fig. 9 and afford a novel beam design of a comparatively effective section wherein the compressive stresses are concentrated or localized in the compression section of the beam above such openings to develop more of a truss action rather than a beam action. Obviously, these openings might be of other form or configuration as for instance, triangular openings alternately reversedly disposed, that is, the apex of one triangular opening to be pointed toward aisancey the upper flange of the beam and the apex of the adjacent triangular opening to be pointed downwardly toward the lower flange of the beam The upper edge of these openings 26D to be approximately at the meeting line of the face of the web 26B with the angular face of the upper flange of the beam.

The precast concrete floor slab 21 as shown in Figs. 13, 14 and 15 consists of a flat body of minimum thickness having spaced end and intermediate c ross ribs 21A each reinforced with a bar 33 which extends at both ends beyond the corrugated sides 21 of the, slab and the ends of which are preferably bent as shown in Fig. 12 for hooked embedment within the bonding and interlocking concrete element indicated by numeral 34 shown in Figs. l and 2. The'longitudinallyextending sides 21c are of increased cross-section 'and also reinforced as with bar 35.

It will be noted that the precast floor slabs 21jare substantially less in width than the spacing of the precast ioists 26 and that they are supported on the joists 26 a spaced distance apart which not only facilitates their installation where such joists might not be exactly spaced, but which slab spacing primarily provides the desirable space for the concrete which is poured at the construction site to constitute the bonding and interlocking element 34. This bonding and interlocking element 34 is reinforced by a longitudinally extending bar 36 which is engaged within the extended loop ends 3M of the joist stirrups 3|.

It will now be readily apparent from the various illustrations that the poured element 34 constitutes a very important feature of my invention since it interlocks the sides of the slabs with the beams or joists. The reinforcing bar 36 of the `poured element is connected by the stirrups 3i to the beam 26 and the slabs 21 are interlocked with the element 34 not only through the extended hooked reinforcing bars 33 but through the corrugations in their sides and thus these corrugations resist the. lateral stresses in the upper flange of the composite T-beam section which includes the upper portion of the joist 26, adjacent portions of the slabs 21 and the interlocking bonding element 34.

Fig. 8 illustrates a side elevation of a typical precast floor joist 26 showing the spaced openings 26D in the middle one-third section of the length of the beam, and in Fig. 9 are shown conduits 32 extending through the joist openings 26D to an outlet box 31 which is supported on the channels 38 which are provided with bent ends 38A hooked for support on the lower flanges 26 of the joists.

As clearly shown in Fig. 11 the wire mesh 39 for the plaster ceiling 40 is secured to the spaced channels 38 by wired connections 4l. An electric light fixture is indicated by 42.

In Fig. 10 the conduits 32 and the outlet box 31 are disposed in the plane of the spaced wood sleepers 43 between the wood floor 44 and the top of the precast slabs 21.

Figs. 16, 17 and 18 illustrate my improved fireresistant connection for inter-framing of joists with cross-joists as for instance, around floor openings or stair wells. In these illustrations 26X indicates a pair of joists supporting a crosse header 26W which includes a steel saddle comprising an angle 45 bent U-shape and riveted to a steel plate 48. V'I'he steel saddle is mounted on the side face of the web of the cross-joist or header 28W between the beveled face portion of the upper flange and the lower flange thereof and is secured to the Webby bolts 41 'which are adapted to be embedded in the web.

It will be noted that in all of these connections the steel saddle is encased with a block of concrete extending on both sides `and bottom of the U-shaped angle and outwardly to the edge of the outstanding leg of the angle 45 so that the steel saddle is surrounded by a protective casing of concrete indicated by numeral 48.

'I'he joist which carries the saddle is cast in each case with a recess 26Y in the upperflange of the beam. This recess 26Y extends longitudinally lof the joist to points slightly beyond the inner crete of the saddle and that this recess 2BR extends inwardly of the end of the joist and upwardly through the lower flange into a portion of the web of the joist at its plane of support in the saddle.

It may bestated that the distance between the inner faces of the parallel Vertical portions of the outstanding leg of saddle angle is slightly greater than the width or thickness of the web of the joist to be supported therebetween.

I claim:

1. A reinforced precast concrete T-beam cornprising a flange portion in the compression section thereof, an integral depending stem portion, reinforcing members in said flange portion and in the tension section of said stem portion, and a plurality of spaced stirrups disposed vertically through said beam, each of said stirrups having an intermediate looped portion disposed above the top of said flange portion and the ends thereof looped about the reinforcing members in the tension section of said stem.

2. A reinforced precast concrete T-beam comprising a ilange portion in the compression section thereof, an integral depending stem portion, a pair of spaced reinforcing members extending longitudinally of said flange portion, a plurality of spaced reinforcing cross-members having ends connected to said flange reinforcing members, a pair of spaced reinforcing members extending longitudinally of the beam in the tension section of said stem portion, and a plurality of spaced stirrups disposed vertically through said beam, each of said stirrups having an intermediate looped portion disposed above the top of sa'id flange portion and each end thereof looped about .one of said stem reinforcing members.

3. A precast concrete beam as embodied in claim 2 wherein said stem includes a plurality of spaced circular openings within the middle one-third section of the length of the beam, said openings being substantially of a diameter not exceeding one-third of the depth of the beam and being spaced substantially a distance of two to three diameters center to center.

4. A reinforced concrete beam comprising an upper flange portion in the compression section thereof, a lower flange portion of comparatively decreased cross-sectional width, a web formed integrally with said flange portions of a cross-sectional width less than that of said lower flange, a plurality oi' spaced reinforcing members extending longitudinally of each of said flanges, a plurality of spaced reinforcing cross-members connecting the reinforcing members in the upper iiange, and a plurality of spaced stirrups disposed vertically through said upper flange and web, each of said stirrups having an intermediate .looped portion extending above the top of said 6. A reinforced precast concrete beam as eml bodied in claim 4, and including a plurality of spaced circular openings extending through said web. said circular openings being located within substantially the middle one-third section of the length of the beam and substantially of a diameter not exceeding one-third of the depth of the beam and spaced substantially a distance of two to three diameters center to center.

l7. A light weight concrete floor structure of minimum weight comprising a plurality of spaced reinforced precast concrete joists of T-beam section. a plurality of reinforced precast concrete slabs of minimum cross-section having spaced cross-ribs with a reinforcing member in each of said cross-ribs extended at its ends beyond the sidesof the slab, said slabs being arranged in spaced rows.A for support on said joists in such manner as to leave a channel therebetween over the center of said joists and having downwardly outwardly battered corrugated side faces defining said channels, a pair of spaced longitudinal reinforcing members in the compression and tension sections of each of said joists, a plurality of spaced reinforcing stirrups extending vertically of said Joistsihaving intermediate looped portions extended above the top of said Joists into said channels, a concrete bonding and interlocking element poured into said channels flush with the top of said slabs, and a reinforcing member extending longitudinally within said poured concrete element and disposed within said looped portions of said stirrups.

8. A concrete floor structure comprising a plurality of spaced reinforced precast concrete T- beam ioists, a plurality of reinforced precast concrete slabs supported in spaced rows on the flanges of said T-beam ,ioists so as to leave a channel over the center of said joists between adjacent sides of said slabs, transverse reinforcing mem-4 bers in said slabs having ends thereof extended into said channels, spaced reinforcing stirrups in said joists having looped portions extending above said joists into said channels, a concrete bonding and interlocking element poured into said channels flush with vthe top of said slabs, and a reinforcing member extending longitudinally within said poured concrete bonding element disposed within said looped portions of said stirrups whereby adJacent portions of said slabs increase the effective compression flange section of the joists, said slabs having corrugated sides defining said channels for said poured concrete.

9. A comparatively light weight reinforced precast concrete floor slab having a body with a smooth level upper face. said body being of minimum cross-section with spaced end and intermediate integral cross-ribs formed on the lower face of said body, said cross-ribs merging with longitudinal ribs formed on the lower face of vthe body at the sides of the slab and having downwardly battered and transversely corrugated outer faces, a reinforcing rod in each of said crossribs, and a reinforcing rod in each of said longitudinal side ribs, said cross-rib, reinforcing rods having ends extended beyond the corrugated side faces and bent for interlocking engagement within a poured concrete bonding element between spaced rows of such slabs. y

JOHN A. S'I'ROMBERG. 

